The present invention relates to a channel switching apparatus for switching a communication channel when a communication quality in a radio communication is deteriorated, and to a channel switching method.
A conventional channel switching apparatus is structured to improve the communication quality by switching the communication channel when the communication quality is deteriorated during communications. This switching is performed on the basis of only a frame error rate and an absolute level of reception electric field strength of a receiving signal to which a desired wave and an interference wave are added.
However, in such a conventional channel switching apparatus, reception electric field strength of each of the desired wave and the interference wave is not determined. For this reason, there is a case in which the communication quality of the communication channel cannot be correctly grasped so that the channel switching cannot be appropriately performed.
In order to solve the above problem, an object of the present invention is to provide a channel switching apparatus, which can correctly grasp the communication quality of the communication channel so as to perform an appropriate channel switching and to improve the communication quality.
In order to attain the above object, the channel switching apparatus of the present invention comprises desired wave reception electric field strength detecting means for detecting desired wave reception electric field strength of a mobile station, and interference wave reception electric field strength detecting means for detecting interference wave reception electric field strength in the same frequency. Then, a ratio of reception electric field strength detected by these detecting means is obtained, and the communication channel is switched based on the obtained ratio. This can bring about stable communications by switching the communication channel when the communication quality of the communication channel is deteriorated even if the absolute reception electric field strength level is high.
Also, the channel switching apparatus of the present invention comprises storing means for storing a comparison result between the reception electric field strength of the desired wave and the that of the interference wave and a detection result of frame error rate detecting means, respectively, and predicting means for predicting a future network state from both the stored comparison result and detection result. This can absorb the variations in the desired wave electric field strength and the interference wave electric field strength caused by fading or a calculation error. Also, this can prevent from erroneously switching the channel, thereby making it possible to obtain an appropriate channel switching. Also, the communication channel can be switched based on a predicted result in advance before the communication quality is completely deteriorated so that communications are difficult to be executed. This makes it possible to ensure the stable communications.